Primary Minerals and Age of The Hydrothermal Quartz Veins Containing U-Mo-(Pb, Bi, Te) Mineralization in the Majersk á Valley near ˇCuˇcma (Gemeric Unit, Spišsko-Gemersk é Rudohorie Mts., Slovak Republic)

: An occurrence of vein U-Mo mineralization is located in the Majersk á valley near ˇCuˇcma, about 7 km to the NNE of the district town of Rožˇnava (Eastern Slovakia). Mineralization is hosted in the acidic metapyroclastics of the Silurian Bystr ý Potok Fm. (Gemeric Unit), and originated in the following stages: (I.) quartz I, ﬂuorapatite I; (II.) quartz II, ﬂuorapatite II, zircon, rutile chlorite, tourmaline; (III.) uraninite, molybdenite, U-Ti oxides; (IV.) pyrite I, ullmannite, gersdorfﬁte, cobaltite; (Va.) galena, bismuth, tetradymite, jos é ite A and B, Bi 3 (TeS) 2 mineral phase, (BiPb)(TeS) mineral phase, ikunolite; (Vb.) minerals of the kobellite–tintinaite series, cosalite; (VI.) pyrite II; (VII.) titanite, chlorite; and (VIII.) supergene mineral phases. The chemical in-situ electron-microprobe U-Pb dating of uraninite from a studied vein yielded an average age of around 265 Ma, corresponding to the Guadalupian Epoch of Permian; the obtained data corresponds with the age of Gemeric S-type granites. The age correlation of uraninite with the Gemeric S-type granites and the spatial connection of the studied mineralization with the ˇCuˇcma granite allows us to assume that it is a Hercynian, granite-related (perigranitic) mineralization.


Introduction
Radioactive anomalies in the vicinity of theČučma village, north of the district town Rožňava (Eastern Slovakia), were, in the past, a subject of several repeated geological surveys or mineralogical-geochemical research [1][2][3][4][5][6][7][8][9][10][11][12][13]. These works were focused on the prospecting, possible verification of raw materials resources and more detailed genetic or mineralogical-geochemical study of U, REE and Au ores. Unfortunately, the results of the geological survey did not show their economic significance.
The above-mentioned anomalies are related to the hydrothermal quartz (quartzapatite respectively) veins with U mineralization, which are hosted mainly in metarhyolites and their metapyroclastics, less in graphite-sericite, graphite and chlorite-rich phyllites (Lower Paleozoic, Gelnica Group, Gemeric Unit). The veins are located in the proximity (a maximum of several hundred meters) of the Permian Gemeric granites intrusions.
The presented contribution is devoted to the results of the detailed mineralogical research of primary minerals association, and CHIME dating of uraninite, from the quartz veins with U-Mo mineralization (the above-mentioned B type), which, thus far, has been insufficiently investigated. These veins are characterized by a unique mineral association, and the mineral phases often have an unusual chemical composition or are rare also on a global scale. In addition, CHIME dating of uraninite clarifies the genetic relationship of the vein U mineralization in the Gemeric Unit to the Permian S-type granite magmatism and brings new insights into the issue of the Western Carpathians metallogeny.

Regional Geological Setting
The Gemeric Unit is one of the most important tectonic superunits in the Western Carpathians. In the north, it is thrusted along theČertovica tectonic line over the Tatric Unit; in the south, the Gemeric Unit is limited by the Lubeník-Margecany tectonic line, which separates it from the overlying Veporic Unit ( Figure 1A). The Gemeric Unit forms a system of north-vergent partial nappes that are composed mainly of metamorphic pre-Carboniferous complexes and Late Paleozoic (to-Lower Triassic) syn-and post-orogenic formations [14]. It is most often divided into a northern (Klátov, Rakovec,Črmel' and Ochtiná Units) and a southern (Gelnica Group and Štós Unit) part. The Gelnica Group is represented by several thousand meters of thick Paleozoic volcanogenic (rhyolite-dacite) flysch [15,16], and its origin was associated with an active margin of Gondwana [17,18]. Both sedimentary and volcanic rocks have undergone regional metamorphism under the chlorite zone of the greenschist-facies conditions [19,20]. The Gelnica Group is, from the bottom to top, divided into the Vlachovo, Bystrý Potok and Drnava Formations (sensu [16,21,22]) intruded by the Permian S-type Gemeric granites [23]. According to geophysics data, these are apophyses of a larger granite body underlying metamorphosed volcano-sedimentary sequences of the Gemeric Unit [24].
All three of the following formations (sensu [16,21]) of the Gelnica Group: the Vlachovo Fm. (Lower-Middle Silurian), the Bystrý Potok Fm. (Middle Silurian) and the Lower Devonian Drnava Fm. ( Figure 1B) are present within the studied area. The Bystrý potok Fm. is the most widespread, formed mainly by lydites, quartz-sericite or graphitic phyllites, metamorphosed rhyolites, dacites and their pyroclastics. Although, according to published geological maps, the Bystrý Potok Fm. is stratigraphically assigned to the Silurian [16], its magmatic rocks yielded Middle-Late Ordovician U-Th-Pb SHRIMP zircon ages of 465.8 ± 1.5 Ma [18,25] and 460-465 Ma, respectively [26]. According to a concept by Grecula et al. [27,28], rhyolite metapyroclastics rocks (so-called porphyroids) of the Bystrý Potok Fm. are included in the Smolník Fm., and metasediments presented as eyed to gneissed metapelites, quartzites or quartzite gneisses represent the Betliar Fm. The Drnava Fm. formed by quartz, chlorite-sericite, or graphitic-sericite phyllites with acidic metapyroclastic rocks is defined by Grecula et al. [27,28] as the Betliar Fm. The metacarbonates of the Vlachovo Fm. are also considered as part of the Betliar Fm. These authors present the stratigraphic range of both the Smolník and the Betliar Formations as Ordovician to Devonian.  [22].

Localization and Geology of The Studied Occurrence
The occurrence of the vein U-Mo mineralization is located in the Majerská valley nearČučma. The site is located about 7 km to the NNE of the district town Rožňava The studied vein with U-Mo mineralization is hosted in the acidic metapyroclastics (porphyroids) of the Silurian Bystrý Potok Fm. ( Figure 1B). Three veins, arranged in accordance with the metamorphic foliation of the surrounding rocks, were discovered in the area of the Majerská valley occurrence in the 1960s. The veins have a direction of 65-67 • to the NE, with a dip of about 36 • to the SE. They are 0.1 to 0.3 m thick and reach a length of up to 50 m. The veins have a lenticular character, to thin out rapidly along strike and dip [1]. The mineralogy of the primary minerals of this occurrence has not yet been studied in more detail. Only quartz, apatite, uraninite and pyrite have been described within the primary vein filling [1].

Methods Used
Field samples were collected using an SGR scintillation radiometer (sample activity measured in cps), at a measuring range (sensitivity) of 400-3000 keV and a measurement step of 0.2 s. Uncovered polished sections were then made from the samples for microscopic study in both transmitted and reflected light.
The distribution maps of the individual elements in a typical ore material were made using X-ray fluorescence spectroscopy (XRF) at the Institute of Earth Sciences SAS in Banská Bystrica, using an M4 TORNADO instrument (Bruker) under the following conditions: current, 50 kV; voltage, 600 µA; range, 40 keV/130 kcps; and measurement time, 2 h.
Chemical analyses of the mineralized samples were performed using the Inductively Coupled Plasma-Emission Spectrometry (ICP-ES) and Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) analyses (ACME Analytical Laboratories Ltd., Vancouver, BC, Canada).

Character of Mineralization
Quartz is a dominant gangue mineral. It has a white to grey-white color locally with a slight pinkish tint. Quartz gangue is relatively compact, and small drusy cavities are rare. Accessory minerals are represented by fluorapatite, zircon, titanite, muscovite, chlorites, tourmaline (schorl to dravite), rutile, leucoxenized Fe-Ti oxides and, rarely, U-Ti oxides. U-Mo mineralization (represented mainly by uraninite and molybdenite) is distributed very irregularly. Macroscopically, it forms dark smudgy accumulations, or irregular fine-grained bands or veinlets in the quartz (up to 5-6 cm in size, Figure 2). Quartz is weakly limonitized in the vicinity of accumulations of U-Mo minerals. The radioactivity of individual collected samples is reaching up to 600-700 cps. U-Mo mineralization is often accompanied by younger, sulphidic mineralization (pyrite, sulphotellurides, sulphosalts, etc.). The chemical composition of the average mineralized gangue is illustrated in Table 1. The distribution of the individual major elements in the vein is shown in Figure 3.  Molybdenite always appears in close spatial association with uraninite, over which it usually predominates. It forms rich accumulations up to several cm in size, which consist of individual flaky crystals up to 20 µm long (Figure 4a). Molybdenite forms rims on uraninite aggregates, respectively enclosing them (Figure 4b). The spaces between the individual molybdenite crystals are locally filled with aggregates of supergene wulfenite ( Figure 4c). The chemical composition of the molybdenite fromČučma is close to the ideal formula. Only a slightly increased content of Fe (up to 0.11 wt. %; 0.003 apfu) was determined using WDS analysis.
Uraninite is the second most widespread ore mineral after molybdenite. It forms globular aggregates up to 0.1 mm in size (the average size of globules is about 30-40 µm) and their clusters (also irregular aggregates), in direct association with molybdenite ( Figure 4a-c). Locally, it also forms grains enclosed in fluorapatite. The supergene degradation of uraninite is manifested by the formation of uranyl phosphates, especially saléeite and bassetite in the close vicinity of its aggregates (Figure 4d).  The chemical analyses of the uraninite fromČučma are given in Table 2. The uranium content is relatively high and stable (0.86-0.87 apfu of U), indicating that uraninite was practically unaffected by younger hydrothermal processes. Similarly, the low Si content (reaching up to 1.54 wt. % SiO 2 ; 0.07 apfu of Si) excludes the possibility of its later coffinitization. Thorium concentrations are very low, under the detection limit of the electron microprobe. From the other elements, the contents of Pb   All uranium is considered to be tetravalent.
The chemical in situ electron-microprobe U-Pb dating of uraninite (according to [29]) provided an age interval of between 241 and 269 ± 2 Ma (2 samples, 23-point analyses; Table 3). However, the majority of the age data obtained (22-point analyses) fall into the range of 261-269 ± 2 Ma (with an average of 265 ± 2 Ma), corresponding to the Guadalupian Epoch of Permian. Unspecified, non-stoichiometric U-Ti oxides are present only infrequently as irregular, metamict aggregates up to 0.15 mm in size, partially intergrown with molybdenite and uraninite (Figure 5a). Leucoxenized Fe-Ti oxides, without uranium occur in similar positions.
Pyrite is a frequent mineral. It was found in association with uraninite, molybdenite, minerals of the kobellite-tintinaite series, sulphotellurides and ullmannite. Pyrite (I) forms irregular to botryoidal aggregates up to 5 mm in size without chemical zoning in quartz. It grows on uraninite globules and encloses (?) grains of joséite-B. Minerals of the kobellite-tintinaite series grow on its aggregates (Figure 5b). Veinlets of pyrite II (distinct chemical zoning) cut accumulations of molybdenite and kobellite-tintinaite series minerals (Figure 5c). Pyrite is, to a great extent, intimately replaced by supergene oxide minerals (or their mixture), which is reflected in the low totals of microprobe analyses (Table 4) and varying ratios of cations and sulphur (0.51-0.60). The high susceptibility of pyrite to weathering processes can most likely be explained by its instability, caused by the significantly increased contents of Bi (0.01-0.07 apfu), Sb (0.01-0.06 apfu), Pb (up to 0.01 apfu) and Cu (up to 0.01 apfu) in the original (not weathered) mineral phase. Ullmannite is a rare mineral. It was found in close spatial association with kobellite in the form of elongated grains, up to 0.2 mm in size (Figure 5d). Ullmannite is usually replaced and overgrown by kobellite, joséite-B and supergene Pb-Bi-Sb oxides. The chemical composition of ullmannite is relatively monotonous and its calculated empirical formula is close to the ideal composition of this mineral (Table 5). Only slightly increased contents of Bi and Se (both below 0.01 apfu) were detected in studied ullmannite. Gersdorffite was found only in one case. It forms an irregular grain, about 10 µm in size, overgrown with the supergene uranyl arsenate -zeunerite (Figure 5e), in quartz cavity. The chemical composition of gersdorffite was verified only by non-standardized EDS analysis.
Cobaltite occurs only rarely as individual, euhedral to subhedral crystals up to 30 µm in size, either enclosed in quartz or growing over pyrite (Figure 5f). The quantitative chemical analyses of cobaltite are shown in Table 6. The two compositional varieties of cobaltite were distinguished ( Figure 6) with the following average empirical formulae: (Co 0.57 Ni 0.22 Fe 0.20 ) Σ0.99 As 0.98 S 1.02 and (Co 0.80 Fe 0.14 Ni 0.06 ) Σ1.00 As 0.90 S 1.10 .     Joséite-A is relatively common as anhedral grains up to 10 µm, enclosed in pyrite together with minerals of kobellite-tintinaite series (Figure 7b). The chemical composition of the studied joséite-A is close to the ideal composition of this mineral phase (Table 7, Figure 8). The most important admixture in the joséite-A fromČučma is the content of Pb, ranging from 0.93 to 1.  Bismuthinite can be divided into two types (A and B), based on the significantly different Sb contents in both types (Table 9) Table 9).
Minerals of the kobellite-tintinaite series are relatively abundant at the studied occurrence. They form individual acicular crystals up to 1 cm long (Figure 9a) or irregular aggregates up to 2 × 2 cm enclosed in quartz and are always in close proximity to uraninite and molybdenite veinlets. Kobellite-tintinaite mineral phases were found in close association with pyrite, jamesonite, cosalite, sulphotellurides and ullmannite (Figure 9b) as well as minor amounts of galena and native bismuth. Their aggregates are replaced, to various degrees, by oxyplumboroméite (sometimes complete pseudomorphs) and other unspecified oxides of Bi and Pb (Figure 9b,c). The chemical composition of the studied mineral phases (Table 10) Figure 10c). The overall Cu+Fe content is between 1.90 and 2.68 apfu (2.03 apfu on average), with Fe negatively correlating with Cu (Figure 10d). Based on the Ag content, the following two groups of minerals of the kobellite-tintinaite series (Figure 10a) can be distinguished: mineral phases with zero Ag content and phases with a slightly increased Ag content (reaching up to 0.24 wt. %; 0.13 apfu). In the second case, Ag negatively correlates with Pb. A small amount of Se (up to 0.61 wt. %; 0.46 apfu) is always present in the anionic position and it shows a slightly negative correlation with S (Figure 10f).
Cosalite is an infrequent mineral, and it forms irregular aggregates reaching up to 80 µm, which are closely associated with minerals of the kobellite-tintinaite series and sulphotellurides (Figure 9d). The studied cosalite has a relatively homogeneous chemical composition (Table 11, Figures 11a and 12).        Jamesonite forms irregular veinlets (with a length of up to 1 mm) in quartz (Figure 9e) or subhedral grains and aggregates up to 150 µm that are intimately intergrown with minerals of the kobellite-tintinaite series (Figure 9f). Supergene Fe-Pb-Bi oxides fill the fissures in the jamesonite or replace it. In terms of chemical composition, the studied jamesonite is interesting mainly due to the relatively stable admixture of Bi (with an average of 16.48 wt. %; 1.77 apfu; Table 12). Rarely, the Bi content reaches up to 24.   Figure 12).  Galena occurs as subhedral grains up to 20 µm in size or aggregates intimately intergrown with bismuthinite and minerals of the kobellite-tintinaite series (Figure 7e). The chemical composition of galena is given in Table 13. From the admixtures, Bi (up to 0.01 apfu) and Se (up to 0.07 apfu) are relatively important, while the content of other elements is insignificant. The average empirical formula of the studied galena is (Pb 0.97 Bi 0.01 ) Σ0.98 (S 0.96 Se 0.07 ) Σ1.03 .

Non-Ore and Accessory Minerals
Quartz is a dominant component of the gangue. In the transmitted light, the two generations of quartz were identified. Quartz I forms weakly undulous, anhedral grains (up to 5 mm in size), embedded in quartz II. Edges of these grains are partially melted and recrystallized. Quartz II is an essential part of the gangue. It is fine-grained, the size of individual anhedral grains is around 0.1-0.2 mm. The undulosity was not observed. Ore minerals are accumulated mainly at the interfaces of quartz I and II aggregates but penetrate both quartz generations.
Fluorapatite is a typical and the most wide-spread accessory mineral of the gangue. It forms subhedral crystals (with square cross-sections), or anhedral grains up to 0.5 mm in size, irregularly scattered in both generations of quartz or in close spatial association with U-Mo minerals (Figures 4d and 13a). Therefore, this position probably indicates at least two generations of fluorapatite. Locally, fluorapatite is overgrown with aggregates of uraninite, and cracks or cavities in fluorapatite are filled with supergene uranyl minerals (Figure 13b). Fluorapatite from the Majerská valley is generally characterized by an overall low content of admixtures and, besides Ca and P (Table 14)  Zircon was found mainly in quartz II. It forms thin, long prismatic crystals with lengths of up to 50 µm. Aggregates of flaky crystals of unspecified chlorites fill thin fissures or small cavities in the quartz. Chlorite aggregates are also developed in interstitial spaces between ore minerals (uraninite, molybdenite, tetradymite; Figure 7a). Small veinlets of titanite rarely cut molybdenite veins, enclosing aggregates of molybdenite crystals (Figure 7a). Rutile forms irregular grains (up to 50 µm in size), enclosed in uraninite and molybdenite, respectively, by supergene uranyl minerals (Figure 13a). Minerals of the tourmaline group (schorl to dravite) occur as individual acicular crystals up to 3 mm or as irregular nests up to 1.5 cm in size enclosed in quartz.

Succession of Mineralization
The microstructural relationships of vein filling minerals suggest that the studied mineralization originated, most probably, in the following stages: (  [5] states that U-REE mineralization in quartz-fluorapatite veins neař Cučma (Gemeric Unit) is accompanied by younger quartz, Fe and Fe-Mg carbonates and a diverse range of sulphidic minerals.
According to our own, as well as previous, mineralogical research by Varček [5] or Rojkovič [9], it is possible to divide uranium (and REE)-bearing quartz (±apatite) veins into the following two main types (based on the association of main primary minerals and the content of P and Y + REE): (A) Hydrothermal quartz-apatite veins containing U-REE mineralization (Betliar, Cučma-Kutačka vein, and some veins in the Majerská valley area) are characterized by a high content of P (0.11-3.47 wt. %) and Y + REE (up to 1.23 wt. %). Although Varček [5] reports a rich association of sulphide minerals from the Kutačka vein, this type of mineralization is characterized by a very low to zero sulphide content, as evidenced by the overall low S content (<0.04 wt. %; quartz-apatite vein with U-REE mineralization from the Majerská valley; Table 1). Besides quartz and apatite, major primary minerals are represented by Y-and REE-bearing minerals (such as monazite-(Ce) to monazite-(Nd) and xenotime-(Y)), uraninite, rutile and titanite [5,6,[8][9][10]33,34]. The element association typical of this mineralization type is Si-P-Ca-U-REE. Rojkovič et al. [9] also mentioned increased contents of Pb, Mo and Au. Despite the increased Mo content, molybdenite is a rare mineral in microscopic amounts. From other sulphides, pyrite is relatively abundant, and galena was found only as a minor mineral phase (Števko, unpublished data).
(B) Hydrothermal quartz veins (with no or minor apatite content) containing U-(±sulphidic)-(±Au)-(±REE) mineralization (Hnilec-Peklisko, Gemerská Poloma-Krátka valley, Henclová, Prakovce-Zimná voda and Zlatá Idka). This type of mineralization is characterized by a zero to very low (up to 0.1 wt. %) content of P. The Y + REE content is generally also reduced, compared to the first type of mineralization; their significantly increased content (with an average of 0.17 wt. %) was found only in the Zimná voda locality. Apatite and Y and REE-bearing phases are only accessory minerals. The content of sulphides in this type of mineralization is variable but stable. Besides quartz, the essential primary minerals are represented by uraninite, brannerite (in different quantitative ratios) and rutile, accompanied by tourmaline and rich assemblage of the following sulphidic minerals: Fe-Ni-Co sulphoarsenides, pyrite, chalcopyrite, galena, tetrahedrite, gold, bismuthinite, millerite, sphalerite, pyrrhotite, etc. Molybdenite is very rare in this mineralization type. The typical element association is Si-(P)-(Ca)-U-Ni-Co-Fe-Pb-Bi-Au-Ti-Zr-B.
The studied quartz veins containing U-Mo mineralization from the Majerská valley can be included in the first approximation to the above-mentioned mineralization type B. However, it is necessary to note some of their peculiarities, as follows: • Compared to type A, fluorapatite is only a minor component in the studied veins (it only has the character of an accessory mineral), as evidenced by the XRF map of Ca and P distribution in the gangue ( Figure 3) and a significantly reduced content of those elements (see Table 1).

•
The typical association of the elements in the studied veins is (the elements in parentheses have a less significance) as follows: Si-(P)-(Ca)-U-Mo-(Pb)-(Bi)-(Te).
Therefore, the significantly reduced P content and the abundant presence of sulphidic minerals allow for the classification of the studied veins into the mineralization type B. However, they notably differ from this type of mineralization by the abundant presence of molybdenite as well as an elevated content of Te. In the vein U-(REE) mineralization hosted in the Lower Paleozoic rocks of the Gemeric Unit, molybdenite was only rarely found at the Zimná voda locality [36] andČučma-Kutačka (Števko, unpublished data). In the Gemeric Unit, an abundance of molybdenite, besides uraninite, is a characteristic feature of deposits and occurrences of stratiform, veinlets and stockwork, mainly volcanogenic (or tectonic) U-Mo mineralization hosted in Upper Paleozoic (Permian) rocks of Northern Gemeric (e.g., Novoveská Huta, Košice-Kurišková, Košické Hámre, Matejovce nad Hornádom; [33,34,38]). In general, acidic to intermediate volcanic effusive rocks and their pyroclastics represent a significant source of U and Mo for this type of mineralization [39,40]. The most important and widespread volcanogenic mineralization in the world is associated with felsic, acidic volcanics-rhyolites, e.g., McDermitt and Virgin Valley caldera deposits in the USA [41], Ben Lomond and Maureen deposits in Australia [42,43], or Smolian deposit in Bulgaria [44].
On this basis, the studied quartz veins with U-Mo mineralization in Majerská valley nearČučma can be defined as a separate subtype of the above-mentioned hydrothermal vein mineralization of type B.

Genesis and Age of U-Mo Mineralization
Quartz and quartz-apatite veins containing U and U-REE mineralization are relatively widespread in the Gemeric Unit; however, their exact dating is still scattered. In addition, there are two fundamentally different views on the genesis of this type of hydrothermal mineralization. Rojkovič [34] and Rojkovič et al. [9,36,45] considered mineralization as Hercynian (although without any dating), whereby the Permian Gemeric granites presumably provided fluids and thermal energy. The hydrothermal effect of granites could have caused a mobilization of P, REE and U from the surrounding Lower Paleozoic graphitic phyllites, metalydites and metaphosphates, and a subsequent concentration of these elements in the hydrothermal veins. However, these authors also admit the possible younger, Alpine age of mineralization. On the contrary, the recent electron-microprobe U-Pb uraninite dating fromČučma [10] gave a Paleoalpine age (207 ± 2 Ma; Late Triassic). On this basis, Permian granites are still considered as a possible source of mineralization elements. However, mobilization of P, F, U, REE and Y from granites and their concentration in the hydrothermal veins had to occur during the Late Triassic tectonothermal rejuvenation of the Gemeric Unit [46].
Questions regarding the petrology, geochemistry and age of the Gemeric granites have been solved by several authors. The granitic rocks of the Gemeric Unit represent a distinct type of specialized (Sn-W-F), highly evolved suite with S-type affinity that differs from other granitoids occurring in the Veporic and Tatric Units of the Western Carpathian crystalline basement. They are enriched in fluorine, phosphorus and rare lithophile elements, such as Li, Rb, Cs, B, Ga, Sn, W, Nb, Ta and U (e.g., [23,[47][48][49][50][51] and others). More recent zircon U-Pb and molybdenite Re-Os isotopic dating, as well as the chemical ages of monazite, indicate emplacement of the Gemeric granites and related post-magmatic mineralization during Late Permian period. More specifically, the age of the Hnilec granites (in the tectonic zone so-called Northern Gemeric hotline) ranges from 289 to 238 Ma (with an average of 262 Ma) [46,[51][52][53][54]. The age of the granites emplaced in the Southern Gemeric hotline (Betliar, Elisabeth Mine, Zlatá Idka and Poproč bodies) varies between 303 and 241 Ma (with an average of 266 Ma) [46,51,53].
In theČučma area, granitic rocks do not reach the surface. TheČučma granite was uncovered by mining works on the Gabriela quartz-stibnite vein, and it was also drilled by borehole Sb-3, 700 m to the NE of the studied locality, at a depth of about 330 m below the surface [55].
The chemical in situ electron-microprobe U-Pb dating of uraninite (Table 3) from the studied U-Mo mineralization hosted in a hydrothermal quartz vein, yielded an average age of 265 Ma, corresponding to the Guadalupian Epoch of Permian. The data obtained corresponds very well with the age of the Gemeric granites, especially with the age of the nearby Betliar granite intrusion (268-264 Ma; [51]), outcropping less than 3 km to the NW of the studied locality. The hidden body of theČučma granite is less than 1 km (400-800 m) away from the studied vein. In frame of hydrothermal mineralizations, the age of the studied uraninite (Majerská valley) agrees with the age of molybdenite of pneumatolytic (greisen type) Sn-Mo mineralization (263 ± 0.9 Ma; [54]), directly genetically related to the Hnilec granite body (Figure 14). The dating of studied uraninite clearly confirmed its Hercynian age. The correlation of its age with published data about the age of the Gemeric granites [46,[51][52][53][54] as well as the spatial connection of the studied mineralization with theČučma granite is clearly pointing to a direct connection between post-collisional S-type granites and the studied U-Mo mineralization. This supports the view of Rojkovič [34] and Rojkovič et al. [9,36,45], that the Gemeric granites were donors of fluids, thermal energy and elements such as P, REE, U, etc. In addition, some fluids were mobilized via a hydrothermal effect of granites from the surrounding Lower Paleozoic metasediments. A number of published works have shown that uraninite is sensitive to subsequent post-mineralization processes (e.g., [57][58][59][60][61][62][63]), which are also reflected in the results of dating. From this point of view, the younger age of uraninite obtained from the U-REE-bearing quartz-fluorapatite vein atČučma by Števko et al. [10] (Figure 14) reflect subsequent, Paleoalpine processes and might represent a younger, remobilized generation of uraninite, although the whole mineralization is also originally related to S-type granitic magmatism. Such remobilization of Hercynian, hydrothermal vein U mineralization in the Gemeric Unit is also supported by the dual, Hercynian and Alpine ages acquired by the chemical dating of uraninite from the Zlatá Idka and Prakovce-Zimná voda occurrences (Ondrejka-unpublished data, Ferenc and Kopáčik-unpublished data).
The classification of the vein uranium deposits (summary in [64]) is based on the presence or absence of other mineral components besides U minerals, also on their geological setting. According to these classifications [65][66][67][68], the studied quartz veins with U-Mo and accompanying sulphidic mineralization at the Majerská Valley nearČučma can be qualified as a granite-related (perigranitic) with a complex mineral association (although the representation of other minerals, except uraninite and molybdenite, is inferior).

Conclusions
Quartz and quartz-apatite veins containing U and U-REE mineralization and the accompanying Au and sulphidic mineralization are widespread at several localities, hosted in Lower Paleozoic rocks of the Gemeric Unit. Ore mineralization at the studied hydrothermal quartz vein at the Majerská valley nearČučma is mainly represented by uraninite and molybdenite, accompanied by a diverse association of sulphides, sulphosalts and sulphotellurides. The chemical in-situ electron-microprobe U-Pb dating of uraninite from the hydrothermal veins yielded an average age of 265 Ma, corresponding to the Guadalupian Epoch of Permian; the obtained data correspond with the age of the Gemeric S-type granites, and also with the age of the greisen type Sn-Mo mineralization associated with them. The age correlation of uraninite with Gemeric granites and the spatial connection of the studied mineralization with theČučma granite allows us to assume that it is a Hercynian, granite-related (perigranitic) mineralization.

Data Availability Statement:
The data presented in this study are available on request from the corresponding author. The data are not publicly available because all representative data are contained in this work.